1. Field of the Invention
This invention relates to adhesive compositions for use in composite-based dental restorations. In particular, this invention relates to a simplified, shelf-stable, one-container primer/adhesive dental composition with excellent bonding properties.
2. Brief Discussion of the Prior Art
In the field of dental materials there have recently been developed various primers, adhesives, and primer/adhesive combinations useful for the adhesion of composite dental restorative materials to the tooth. Primers are especially useful for enhancing bonding to dentin after the dentin surface has been cleansed and/or etched. Primers are generally surface-active compounds that exhibit both an affinity for dentine and adhesive resins systems. Primers may participate in the polymerization process, thereby promoting adhesion between the dentine and the adhesive. Known primers include methacrylate-based derivatives of carboxylic acids, phosphoric acids, and derivatives of amino acids such as N-phenylglycine. Especially effective primers include a polymerizable moiety such as a methacrylate, and a surface-active functional moiety such as a carboxylic acid, carboxylic acid anhydride, phosphate, sulfonate, sulfinate, aldehydes, isocyanate, and/or hydroxyl group.
Adhesives are generally in the form of polymerizable resin monomers, for example acrylate and methacrylate-based monomers such as triethylene glycol dimethacrylate (hereinafter TEGDMA), 2-hydroxyethylmethacrylate (hereinafter HEMA), and the like, including viscous resin monomers such as 2,2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy)phenyl]propane (hereinafter Bis-GMA), polyurethane dimethacrylates (hereinafter PUDMA), and the like.
In addition to the above components, dental primer/adhesive compositions may further comprise solvents and curing agents, including chemical, photochemical, and dual-curing free-radical initiators.
There has been increasing interest in "one-container" primer/adhesive compositions, comprising primer, adhesive component, polymerizable resin monomer, and curing agents capable of being provided to the dentist in a pre-mixed, shelf-stable form. Such formulations are convenient for the dentist, as they require no mixing, and primer and adhesive are not required to be applied in two separate steps. Multi-step bonding protocols typical of the current multi-component systems are wasteful of material, and sensitive to technique.
One-container primer/adhesive systems have been disclosed for example in U.S. Pat. Nos. 4,636,533 and 4,640,936 to Janda; and U.S. Pat. Nos. 5,749,733 and 5,658,963 to Qian. Although current adhesive systems such as the foregoing show improvement over their earlier versions, they are still far from ideal. Current systems have complex compositions and application protocols which make dentin bonding an extremely technique-sensitive procedure. Accordingly, there remains a need in the art for improved and simplified one-container dental primer/adhesive compositions with excellent bonding properties.